Drinking water

I drank the water in Slovenia. Can't say about the others.

In all the countries that you have mentioned, tap water is safe to drink. Of course, the quality of the water itself differs a lot. For example, people in Rijeka town on the Adriatic coast, drink literally natural spring water because the tubes of the water supply system are immersed in the spring. In contrast, several towns in the continental part are drinking tap water that arrives from river water treatment plants and some others take their water from water accumulations and subterranean aquifers.

Anyway, the truth is that you cannot get any disease that can be classified as something that has to be cured by antibiotics or similar regardless of the place in all of the mentioned countries.

To be honest, there is one small problem. The truth is that although the water is safe, it can differ from the water that you use to drink on daily basis in terms of its ingredients (almost every water supply system in the world has a bit different ingredients beside H2O in their pipes). Knowing so, it would be advisable that you take two or three days for, let's say, your transitional period to become accustomed to the local tap water. This is not something that should be done, but it is just a recommendation to the travelers with sensitive digestive system that could react and produce highly undesirable diarrhea.

It's good to know I can drink tap water if I have to.
I drank tap water in Spain, England, Scotland, Ireland, Germany from day 1 without any problem but in France I had to switch to bottled water.
I hate to pay for bottled water specially in the restaurants.
Thank you very much.

Tap water in Slovenia, Croatia and Bosnia is very safe to drink. I would recommend to try some mineral water in Bosnia, they have some of the best mineral water in the world.